Three research projects are described related generally to the synthesis, accumulation and distribution of maternal products during oogenesis and oocyte maturation and their utilization and distribution during early development. The first includes studies on the steroid induction of oocyte maturation in vitro. The nature of steroid-oocyte interactions involves studies on ion fluxes, before and after exposure to progesterone, as well as attempts to isolate and characterize a maturation promoting factor which appears in the cytoplasm of oocytes in response to exogenous progesterone. The nature of MPF during cleavage also is being studied as it relates to changes in the cell cycle. The second project involves a quantitative and qualitative study on RNA synthesis in lampbrush chromosome stage oocytes, and full grown oocytes before and after exposure to progesterone. Rates of total RNA synthesis are calculated from kinetics of incorporation of 3H-GTP injected into oocytes, and precursor pool specific activities. Based on separation on polyaccrylamide gels and oligo (dT) columns, rates of synthesis and degradation constants for heterogeneous nuclear RNA, ribosomal RNA, and poly (A) containing RNA are being derived. Likewise, studies on the nuclear-cytoplasmic distribution of the various RNA species are studied as a function of time after injection of radioactive precursor into oocytes. The final project concerns studies on germ plasm during early development, and the effect of ultraviolet irradiation on the formation of germ cells. Using both ultrastructural characteristics unique to germ plasm and analysis of several stages of development ranging from fertilized eggs to tadpoles, attempts are being made to determine if UV irradiation alters germ plasm, or prevents germ cell formation by other means.